Struct DmaController 

pub struct DmaController { /* private fields */ }

The two PC/AT 8237 DMA controllers, serviced one unit per device request.

Models address/count registers, AT page registers, masks, transfer direction, auto-initialization and terminal count. Address/count accesses share one low/high flip-flop per controller. Channel 4 is the cascade and transfers no device data. Only memory-to-device transfers are implemented.

This models register-visible transfer state, without bus arbitration, timing, memory-to-memory transfers or peripheral-to-memory writes. Demand, single and block modes all service one unit per call; cascade mode does not transfer.

Implementations

impl DmaController

pub const fn new() -> Self

Construct two controllers with all channels masked and inactive.

pub fn ports(&self) -> &[PortRange]

I/O ports decoded by the controllers and their seven AT page registers.

pub fn outb(&mut self, port: u16, value: u8)

Write an 8237 register or AT page register. Unknown ports ignore writes.

pub fn inb(&mut self, port: u16) -> u8

Read a current address/count, page or status register. Status reads clear terminal-count flags; other unsupported reads return FFh.

pub fn transfer( &mut self, request: DmaRequest, memory: &ConventionalMemory, ) -> Result<Option<DmaUnit>>

Read one DMA unit and advance the channel only after memory access succeeds. Masked, disabled, exhausted or incompatible requests return Ok(None) without changing channel state.

Byte channels wrap within a 64 KiB page. Word channels shift their 16-bit address by one, ignore page bit zero and wrap within 128 KiB. Count FFFFh means 65,536 units. Terminal count either reloads the base registers in auto-init mode or stops the channel until reprogrammed.

Trait Implementations

impl Clone for DmaController

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for DmaController

impl Debug for DmaController

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for DmaController

fn default() -> Self

Returns the “default value” for a type.